(1) Field of the Invention
The present invention relates to a detection area adjustment apparatus that adjusts the imaging area using internal cameras, especially to an optimum apparatus having such cameras that is used for a monitoring system.
(2) Description of the Related Art
Research and development on an apparatus having cameras that are mainly for the use of monitoring has been actively performed recently. In order to achieve this use purpose, such an apparatus is required (i) to always monitor an entire target detection area (the area in which monitoring is performed) and detect a target detection object in the target detection area, and (ii) to obtain detailed information on the target detection object that is present in the target detection area.
A conventional apparatus having cameras meets the above-mentioned requirements by automatically adjusting the imaging ranges of the respective internal cameras. A typical example of such an apparatus is shown in Document 1 and Document 2.
Document 1: U.S. Pat. No. 3,043,925 publication; and
Document 2: U.S. Pat. No. 3,180,730 publication.
FIG. 1 shows an apparatus that automatically adjusts the imaging areas of those cameras described in the Document 1. In the detection camera apparatus 9010, an image of a target detection object is taken by a camera 9011 and a reflection mirror 9012 in a large imaging area, a moving object extraction unit 9013 extracts the target detection object from the images taken by the moving object extraction unit 9013, and a position information extraction unit 9014 extracts position information on the detected target detection object in the area. In this way, the detection camera apparatus 9010 obtains the position information on the target detection object in the large imaging area that is later called detection area. In the judgment camera apparatus 9020, a camera control unit 9022 controls an angle of traverse, an angle of depression and a zoom ratio of the camera 9021 based on the position information on the target detection object, a judgment camera apparatus 9020 takes enlarged images of the target detection object. In this way, the judgment camera apparatus 9020 obtains detailed information on the target detection object.
FIG. 2 is a diagram showing the detection area of the detection camera apparatus 9010 and the detection area of the judgment camera apparatus 9020. In the figure, each bullet shows the setting position information on the detection camera apparatus 9010 that is a fixed camera. Likewise, each circle and each hexagon show the detection area of each detection camera apparatus 9010. As shown in the figure, setting each detection camera apparatus 9010 at regular intervals on purpose makes it possible to always detect a target detection object in the entire target detection area to be monitored.
FIG. 3 shows an apparatus that automatically adjusts an imaging area of those cameras described in the Document 2. In the figure, a camera for detecting moving objects 9211 is used for the purpose of taking an image of a target detection object in a large imaging area and a monitoring camera 9221 is used for the purpose of taking an enlarged image of the target detection object. The camera for detecting moving objects 9211 adjusts its imaging area by an angle control unit 9212, while the monitoring camera 9221 adjusts its imaging area by an angle control unit 9222.
The imaging area of each camera is determined in the image processing apparatus 9240, taking into account the position of the target detection object that is extracted from the image taken by the camera for detecting moving objects 9211 and the imaging area of each camera, and based on the information that is previously stored in a camera angle memory unit 9231 and a camera angle memory unit 9232.
The method for determining an imaging area of each camera will be described below. FIG. 4 to FIG. 6 are diagrams that are used for describing the imaging area determination method of each camera. Each of the figures is divided into several block images and taken by the camera for detecting moving objects 9211. First, the imaging area of the camera for detecting moving objects 9211 is determined as will be described below. In the case where there is a target detection object in one of the diagonally-shaded blocks in FIG. 4, the angle of the camera for detecting moving objects 9211 is adjusted to the direction shown by the arrow described in the block in FIG. 5 corresponding to the block in FIG. 4 so that the imaging area of the camera is adjusted. The position of the imaging area of the camera for detecting moving objects 9211 is previously determined by someone so that it matches the position of the total area of the block images, and the information on the imaging area is previously set in the camera angle memory unit 9231. Next, the imaging area of the monitoring camera 9221 is determined as will be described below. In the case where there is a target detection object in the block shown in FIG. 6, the angle of the monitoring camera 9221 is adjusted so that the imaging area is also adjusted to the matching area that is enclosed by a broken line. The position of the imaging area of the monitoring camera 9221 is previously determined by someone so that it matches the position of the total area of the block images, and the information on the imaging area is previously set in the camera angle memory unit 9232.
The features of the conventional apparatus having the cameras will be described below. Note that, in this apparatus, each camera detects a target detection object based on the information on the imaging range in which the camera takes images, or obtains detailed information on the target detection object. Therefore, the imaging range of each camera matches the range in which each camera detects the target detection object and obtains the information on the target detection object. Such being the case, the imaging range of each camera will be described as a detection range of the camera from here.
In the conventional apparatuses that are respectively shown in the Document 1 and the Document 2, each camera plays one of the fixed roles that has been previously determined. One of the roles is to monitor the entire target detection area, and the other role is to obtain detailed information. In the Document 1, a detection camera apparatus 9010 plays the role to monitor a target detection object in a large detection area, and a judgment camera apparatus 9020 plays the role to obtain detailed information, such as an enlarged image, on the target detection object. On the other hand, in the Document 2, a camera for detecting moving objects 9211 plays the role to monitor a target detection object in a large detection area, and a monitoring camera 9221 plays the role to obtain detailed information, such as an enlarged image, on the target detection object.
Also, in the conventional apparatus shown in the Document 2, the detection area of each camera is determined and adjusted based on the information that someone previously conceived in a form of a table, the information describing detection areas that are respectively corresponding to the specified adjustment statuses. For example, when there is a status change that the position of the target detection object to be detected by the camera for detecting moving object 9211 is adjusted to the upper left block of FIG. 4, the detection area of the camera for detecting moving object 9211 is also adjusted to the detection area in the upper left direction shown in the upper left block of FIG. 5 in response to the status change.
However, since the entire target detection area is monitored by someone previously setting fixed cameras at regular intervals in the conventional apparatus of the Document 1, in the case where a camera is broken, it becomes impossible to continue monitoring. For example, as shown in FIG. 7, increasing the number of detection camera apparatuses 9010 enables to cover the entire target detection area even in the case where one of the cameras is broken, but it is inefficient.
Also, in the apparatus in the Document 2, since the detection area of each camera is determined and adjusted based on the information that someone previously conceived in a form of a table, the information describing the detection areas that are respectively corresponding to the specified adjustment, someone needs to conceive the information in a form of a table, the information describing the detection areas that are respectively corresponding to the adjustment. The information depends on the position and the breadth of the target detection area, the adjustment conceived by someone, the positions in which respective cameras are set, and the number of cameras. In the case where there occurs a change in the information, someone needs to remake the information in response to the change. This operation becomes more troublesome as the number of cameras increases, resulting in increasing the cost and the workload for performing such operations. It is general that ten cameras are used in the camera monitoring system in a building.